B. Laassis et al., PHOTOCHEMICALLY INDUCED FLUORESCENCE DETERMINATION OF BIOMEDICALLY IMPORTANT PHENOTHIAZINES IN AQUEOUS-MEDIA AT DIFFERENT PH VALUES, Analytica chimica acta, 290(1-2), 1994, pp. 27-33
A simple room-temperature photochemically induced fluorescence (RTPF)
method was developed for the determination of several biomedically imp
ortant phenothiazines including azure A, methylene blue, thionine, pro
methazine and unsubstituted phenothiazine in aqueous solutions. These
compounds are weakly or non-fluorescent under these conditions but the
ir fluorescence can be induced on UV irradiation. The influence of pH
and irradiation time on their excitation and emission fluorescence wav
elengths and on their fluorescence intensity was investigated. It was
found that the optimum PH values ranged from 2.0 for unsubstituted phe
nothiazine to 7.0 for promethazine and 10-13 for the other compounds,
the selected irradiation times being between 5 s and 17 min, depending
on the compound. Linear calibration graphs were obtained over about t
wo orders of magnitude, with relative standard deviations in the range
3.9-6.9%. RTPF limits of detection were between 12 and 70 ng ml(-1) a
ccording to the compound. RTPF was applied to the determination of phe
nothiazines in urine samples. The mean recoveries ranged from 87 to 11
6%.